In many buildings the external walls of buildings are formed of two leaves which are separated by a cavity. In providing such a wall, consideration must be given to the potential accumulation of water in the base of the cavity which may occur during the construction of the building and in particular before a roof is in place and subsequent to the completion of the building as a result of leakage in the roof, or leakage around windows, or overflowing gutters. The effect of such accumulation results in moisture seeping through the exterior and interior leaves of the wall which will result in deterioration of the wall and wall coverings or paint plaster or stucco applied to the wall. In addition seepage through the interior leaf will result in damage to the contents of the building such as the floor coverings.
In an effort to overcome the problem of the accumulation of water in the base of the cavity of a double leaf wall it has been conventional practice to provide a number of "weep" holes at spaced intervals around the base of the outer leaf of the wall. In the case of double brick walls or brick veneer walls these weep holes are usually provided in some of the vertical joints between adjacent bricks of the lowermost course of the outer leaf of the wall.
The problem that arises with this conventional practice is that during the erection of the wall, material such as excess mortar, sand and miscellaneous building debris generated during the building process accumulates in the base of the cavity. In addition on completion of the building other material will accumulate in the cavity over time. Such material can block the "weep" holes which then severely restricts and/or prevents the drainage of water from the cavity. In addition, the debris provides an absorption medium which will retain the moisture within the cavity rather than allowing it to drain from the cavity. In either case, the accumulation and retention of water in the cavity can lead to the decay and deterioration of the two leaves of the wall and any coatings provided on the outer faces of each leaf. In addition such accumulation can result in the entry of water into the building through the internal leaf of the wall which can ultimately lead to mould forming through the plaster and paintwork of a wall as well as the building contents.
It is an object of this invention to provide a drainage means for use in the cavities of building walls.